CO2 Laser Optics/Devices?

PhysicsEngineer · Mar 9, 2011

I am doing a senior project at UW-River Falls with a Synrad 25W CO2 laser (model: 48-2-28(W)) with a wavelength of ~10.6um. Since it was a donation and seasoned, it is only operating at about half the power ~12.5 W/cm^2. Still at this power, it is too much for my energy meter. I am interested in dropping the power down to 5 W/cm^2 or more. All the optics I have in my possession are for HeNe lasers and I am not sure if they are good enough for my CO2 laser.

What devices/equipment is there on a limited budget to decrease this power?

Thank you in advance!!

LSRFAQ · Mar 10, 2011

Beamsplitters for Co2 are neither common nor cheap. You could try a few uncoated silicon wafers if you can find a few around campus. (3$ or so)
A FTIR spectrometer on campus would give you the reflectivity, if you cannot look it up.

The easiest thing to do, but some what difficult to calibrate, is expand the beam and take a known fraction of the area. This can be done with a convex or concave mirror or a lens.

Steve

Cyparagon · Mar 10, 2011

^That sounds tricky since the intensity wouldn't be the same at every point of the beam.

No, virtually none of your optics for HeNe will work for CO2. If you only want to drop the power and not the power density, why not just lower the power to the laser?

PhysicsEngineer · Mar 10, 2011

I have at my disposal many 100 P-type Silicon wafers. Any suggestions on easiest method for decreasing the power, or is it just trial and error? I am going to take measurements using a ELTEC model 420 Pyroelectric Laser Detector and the incident power limit (max) it can take from the laser is 5 W/cm^2.

Also, I was looking into neutral density filters, and I contacted LASNIX and I was told their GF01 model would do the trick, the only problem is that it is $1800 and would take 2 - 5 weeks to deliver. I am under a very limited budget and time frame, so that would not work for me.

Any other suggestions would be greatly appreciated!

PhysicsEngineer · Mar 22, 2011

Can anyone help me...please?

I have the laser ready to operate, I just need to find means of decreasing the output power of the beam. Am I safe with just putting one of the 100 P-type Silicon wafers in the beam path? Or should I start with a number of the wafers back to back?

ANY input will be greatly appreciated!!

Thanks in advance for any/all responses!!

Bluefan · Mar 23, 2011

Aren't pyroelectric sensors for pulsed lasers?

Cyparagon · Mar 23, 2011

I guess you missed my post, so I'll ask again:

Why not just lower the power to the laser?

PhysicsEngineer · Mar 23, 2011

I can decrease the power of the laser and the pyroelectric detector is rated for IR but I am nervous that it may damage the detector. I have already successfully made glass out of my brick backstop.

Should I just go with confidence that the detector will be fine with low enough power and with no use of beam splitters or silicon wafers?

PhysicsEngineer · Mar 23, 2011

I also just looked at the specs of the detector and it says its Incident power limit is 5 W/cm^2 and I am running around 5W at its lowest driving power. It also says that the thermal breakpoint is at 5Hz. I am not sure if this is the same or not, but I have my function generator set at .88kHz for the tickle pulse and first emitting at 8.8kHz for the duty cycle.

(The laser manufacturer's specs show the use of the laser with a UC-1000 controller to which the FG is a substitution for)

PhysicsEngineer · Mar 23, 2011

That last post was TOTALLY off base!! The duty cycle was in us NOT Hz!! :wtf:

Cyparagon · Mar 23, 2011

I bet we could help you better if we knew what you were trying to do. What exactly is your ultimate goal here? If it is only to measure the power of your laser, perhaps you should look into a coffee mug calorimeter.

PhysicsEngineer · Mar 24, 2011

What I am doing is using a 5kHz clock freq (from a function generator) to drive a waveguide CO2 laser. I want to see the relationship between the output signal of the beam to the input signal from the function generator with LabView and a pyroelectric detector. When I had my duty cycle set at 8.8us, and using an old Lasercraft P-200 laser power probe, I was getting around 12 - 15 W. The specs on the probe don't say anything about area when it comes to power. That is where I am concerned with damaging my pyroelectric detector so I am trying to find ways of controlling/decreasing the output power of the beam. I am already running the laser at the minimum driving power, that is the reason to try and split/diffract the beam itself.

I hope this is more clear than my previous posts, and sorry for all the confusion!!

Thank you all very much for your patience with me and your help I really appreciate it!

Cyparagon · Mar 24, 2011

And why do you need to see the relationship?
I don't think your sensor will be fast enough to accurately detect the pulse shape of 5Hz let alone 5kHz.
The beam will diverge on its own and be attenuated by the air itself, so you can probably get away with putting the sensor 30 feet away.

Bluefan · Mar 26, 2011

I've heard of some pyroelectric sensors that can be used with an oscilloscope to see the pulse shape, but I'm not sure about it. Pyroelectric sensor are fast, but I'm not sure if they can measure the pulse profile.

HIMNL9 · Mar 26, 2011

I've read times ago about something called "Mercury Cadmium Telluride sensors" for 9 to 14 um, used for high speed CO2 laser detection using heterodyne systems, but i'm unable to find it back on the internet, at the moment ..... maybe some universities have something about it .....

CO2 Laser Optics/Devices?

PhysicsEngineer

0

LSRFAQ

0

Cyparagon

0

PhysicsEngineer

0

PhysicsEngineer

0

Bluefan

0

Cyparagon

0

PhysicsEngineer

0

PhysicsEngineer

0

PhysicsEngineer

0

Cyparagon

0

PhysicsEngineer

0

Cyparagon

0

Bluefan

0

HIMNL9

0

Online statistics

Forum statistics

Share this page